Equipment for degassing metals in particular steel melts



July 7,- 1959 F. HARDERS ETAL 2,893,715

EQUIPMENT FOR DEGASSING METALS IN PARTICULAR STEEL MELTS Filed FSept. 4, 1956 2 Sheets-Sheet 1 July 7, 1959 F. HARDERS ETAL 2,893,715

EQUIPMENT FOR DEZGASSING METALS IN PARTICULAR STEEL MELTS Filed Sept. 4, 1956 2 Sheets-Sheet 2 United States Patent r0 naeas mc hams N PARTICULAR STEEL MELTS Fritz arder? fic y r e fi l n Hfil l 99m Dortmund Nett'e, aiid Karl" Brotzinann; Dortmund, Germany, assignors to )oi hnund-Horder Huttenunion Aktiengesellschaft, Dortmund, Germany npinicanen September 4; 1956; Si'ialNo. 607,615

priority, application Germany sptember 5, 1955 Z'Cliiiiiisl 01266-34) vltz-isglen ovvn that steel melts may be considerably improved by employing vacuum treatment; Until the presa owe e ther as een a d? an r m n r d a sin t e me cons u t d sufficientlxsimple, an so ex b h t t r .,.b. 9w.m t thg tqbstacles' in the operation of steel Works. According to the invention, this purpose is served by equipment for degassing metals, particularly of steel melts.

The equipment comprises a vacuum chamber and an inlet and outlet pipe, connected thereto in spaced relationship from one another for the melt before and after degassing. Both pipes are barometrically sealed oil from the atmosphere in such a manner that their ends reach into the melt. In the equipment familiar in this art, the barometric seals of the inlets and outlets of the vacuum tanks are connected with a fixed smelting furnace, so that the exposure time of the metal in the vacuum tank and the level to which it is filled can only be changed by the modification of the vacuum. This impairs the flexibility of the equipment for the operation of the steel works and the respective type of melt to be degassed.

In the equipment for the degassing of metals, particularly in melts of steel, according to the invention, the containers filled with the gas-impregnated metal to be degassed are vertically adjustable under the vacuum tanks and are preferably mobile. In the bottom of these are immersed the inlet and outlet pipes and the height of the bath in the vacuum tank, the relative flow velocity of the metal through the vacuum tank, and its character may be matched. Since, according to the invention, the metal formed in the inlet and outlet pipes is heated directly through electrical resistance heat, the metal remains hot and easy flowing at various immersion levels of the pipes.

Since the vacuum tank and both of the pipes immersed in the supply tank must be kept vacuum-tight, the pipes and the vacuum tank are provided on their exteriors with a gas-tight metallic coating.

To prevent the disintegration of the ends of the inlet and outlet pipes, which are immersed in the supply tank, the metallic pipe covers are cooled at these spots and are covered with a ring of heat-resistant material.

A substantial degassing needs exposure time of the steel in the vacuum tank of about a half hour. As the loss of heat which escapes from the bath cannot be compensated by the heat content of the steel melt, the steel melt must also be heated. To this end, a direct electrical resistance heating of the melt in the furnace assembly has proven particularly practical.

The terminals of the secondary winding of a transformer are connected to the metal jacket of the inlet or outlet pipes. The jacket on one of the pipes is electrically insulated from the tank jacket. The immersed parts of the metallic pipe jackets together with the metal column inside the pipe and the metal bath in the vacuum container form a closed electrical circuit by means of which the melt is heated directly. For large installations with a 2 travel velocityof, 50 tons per hour, currents of" about 500 kw. are required. In order 'to obtain these, thesec: ondary of the; transformer, which may be advantageously of the variable type, must carry about 20 volts. The heatt producing cu'iprent of the, transformer can be; automatically controlled, depending on the temperature'of the metal, in the vacuum tank or in the inlet and outlet pipes, i hes pl 't nk-b A In or r o. Braves the'w e t f m flq na thr h he-.ia et fift s v uum an thems lsg i iasen mektim o tlet; i e sai h? an a ns s n u te tram t et m ia s F Y fl Q; .It ma e a a aa q s ins all us i n vla ion ot ip e acke s, in rde hat h sq er naqtt e va uum. t nk shsu s be ind e dent s l'th qtsnt al. 9 thi s r t cond c n part of the equipment, and may, for example, be grounded add ttQn-r. I m

The Q'Qn ain a rs n t e de as edl e m ay be installed'for tilting. The steel may then be poured through a pouring spout. In such a case, no provisions need be made for outlet openings in the bath or in the wall of the container. The level of the metallic bath in the vacuum container as well as the travel velocity of the metal can be regulated by automatic control devices which influence the device for the height adjustment of the supply container.

The invention will now be more fully described in the drawings, but it should be understood that these are given by way of illustration only, and not by way of limitation, and that many changes can be made in the details without departing from the spirit of the invention.

In the drawings:

Fig. 1 shows a vacuum installation in vertical crosssection;

Fig. 2 is an axial cross-section through an inlet or out let pipe; and

Fig. 3 is the submerged part of this pipe.

A vacuum container 1 which is covered with a gastight metal jacket 1 is provided with a heat-resistant bricklining. Suitable equipment connected with the preferably multi-stage container, e.g. pump conduits, as well as arrangement for supplying the materials for chemical treatment, are not shown. To the vacuum chamber are connected an inlet pipe 3 and an outlet pipe 4. The pipes open into the bath of the chamber and have their free ends immersed in a supply vessel 5 or 6 for the degassing or degassed steel, respectively. These vessels are adjustable in height.

A transformer 7 is employed to heat the steel melt. For this purpose, its secondary winding 7' is connected on one side with the metal cover of pipe 3 and on the other side to pipe 4. To prevent a short circuit over the con tainer jacket 1, the cover of pipe 4 is insulated from the remaining covering 1 by an insulation 8.

Fig. 2 shows that the insulation consists essentially of two circular flanges 9, 9', which encircle the heat-resistant covering 10 of the pipes, and are provided with circular grooves 11, 11 for receiving a coolant. An insulating layer 13 is found between the grooves, as is a circular seal 12, and these are secured against axial or radial movement.

The bracing of the upper and lower flanges is accomplished through a ring 14. 15 is an insulating annular member.

Fig. 3 shows that the inlet and outlet pipes are conically expanded at their ends. Since the cross-section of the inlet channel 16 is unchanged, there is provided at this particular point a reinforcement of refractory masonry and increased heat protection for the metal at this sensitive point. The metal covers 17 is covered with a frustoconical ring 19 which is formed of refractory material.

The arrows 20 and 21 indicate the limits within which the bath level of the melt fluctuates. topped by a cooling chamber 22.

What we claim is: 1

1. A device for the degassing of metal melts which comprises, in combination, a vacuum chamber for holding said metal; a pair of supply vessels, one of said vessels being filled with degassed melt, the other with melt to be degassed, each of said vessels being adjutable in height; an inlet pipe and an outlet pipe, each hermetically sealed at one end to said chamber and connected at the other end to an opening in one of the vessels and extending into said melt, the upper ends of said inlet pipe and outlet pipe being flush with the bottom of said vacuum chamber; said inlet pipe and outlet pipe being made of refractory material, and the pipes as Well as the vacuum chamber being enclosed in a metal sheath which at the end of the inlet and outlet pipes is covered by a ring of refractory material, the terminals of a secondary winding of a transformer being connected to the sheath of the inlet and outlet pipes; one of said pipes being electrically insulated from the sheath of the vacuum chamber, whereby a closed electrical circuit is formed by the metal The ring 19 is 4 sheaths of the two pipes, the metal melt within said pipes, and the metal melt within the vacuum chamber.

2. The structure according to claim 1, wherein the electrical insulation between the sheaths of the pipes and the vacuum chamber consists of cooled annular flanges, between which are disposed an insulating layer secured against axial and radial displacement, as well as a vacuum seal.

References Cited in the tile of this patent UNITED STATES PATENTS 1,068,643 Franklin July 29, 1913 1,912,316 Stall May 30, 1933 1,921,060 Williams Aug. 8, 1933 1,944,733 Doerschup et a1. Ian. 23, 1934 2,054,923 Betterton et a1. Sept. 22, 1936 2,102,582 Summey Dec. 14, 1937 2,140,607 Thompson Dec. 20, 1938 2,568,578 Bennett Sept. 18, 1951 2,587,793 Waldron Mar. 4, 1952 2,734,244 Herres Feb. 14, 1956 2,772,517 Bowes Dec. 4, 1956 

